This invention relates generally to the field of image sensors and, more particularly to, such image sensors having vertical charge-coupled devices that capture high light levels and photodiodes that capture low light levels for extending the dynamic range of the image sensor.
A typical interlined charge-coupled device includes a plurality of photosensitive areas for capturing incident light and generating electrons representative of the captured image. The charge-coupled device also includes a plurality of charge-coupled devices disposed respectively adjacent the photosensitive areas for receiving electrons generated from the photosensitive areas and for transporting the electrons to other circuitry, as is well known in the art. A plurality of metal shield respectively covers the plurality of charge-coupled devices for preventing the incident light from exposing them.
Although the presently known and utilized interlined CCD is satisfactory, improvements are always desirable. In this regard, it is sometimes desirable to capture high levels of light that are lost when photosensitive areas become saturated.
Consequently, a need exists for an interlined CCD that includes the above-described improvement.
The present invention is directed to overcoming one or more of the problems set forth above. Briefly summarized, according to one aspect of the present invention, the invention resides in an image sensor having a plurality of pixels each including a plurality of photosensitive areas having a first sensitivity to light for forming a first sensitivity area, a plurality of charge-coupled devices respectively adjacent the photosensitive areas having a second sensitivity to light for forming a second sensitivity area; wherein the second sensitivity area is less sensitive to light than the first sensitivity area so that the second sensitivity area saturates after the first sensitivity area saturates, and a first transfer mechanism for permitting electrons to be passed from the first sensitivity area to the second sensitivity area; and the image sensor also including a second transfer mechanism for moving electrons through the plurality of charge-coupled devices.
These and other aspects, objects, features and advantages of the present invention will be more clearly understood and appreciated from a review of the following detailed description of the preferred embodiments and appended claims, and by reference to the accompanying drawings.
Advantageous Effect of the Invention
The present invention has the following advantage of capturing high levels of light by the charge-coupled devices for extending the dynamic range of the image sensor.